Fire-alarm trunk switching mechanism.



D. G. DEE.

FIRE ALARM TRUNK SWITCHING MECHANISM.

APPLICATION FILED FEB.25;' I9I4.

1,225,936., Patented May15,1917.

+ of trunk unrrnn sra rnsr irnnr camera DAVID G. DEE, OF ROCHESTER, NEW YORK, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

ROCHESTER IE1. ROGERS, .035 ROCHESTER, NEW YORK.

FIRE-ALARM TRUNK SXVITCHING- MECHANISM.

Application filed February 25, 1914.

1% lire alarms or signals may be despatched from a telephone subscribers substation to the central office or exchange and from there to the department headquarters, and it has for its object to provide a novel arrange- .1 meat of apparatus whereby the use of one of several. different alarm trunks leading to fire department headquarters will automatically distribute subsequent calls onto other trunks, thus preventing two or more operators from connecting two different circuits on which fire alarm calls may be received simultaneously at the central office, to one and the same trunlr. To these and other ends the invention consists in certain improve- 1 merits and combinations of parts, all as will lei'einafter more fully described, the novel features being pointed out in the claims i the end of the specification.

the drawings:

ie figure is a diagrammatic illustration showing the central office switchboard mechanism, subscribers circuits and a plurality of trunks leading to department head-- piarters, together with the automatic switching devices controlling the distribution of calls over said trunks.

In practice, l. have determined that for accuracy in operation and in order to avoid confusion it is desirable to have a plurality ircuits leading from the central exchange or telephone ethics to the fire alarm headquarters, and l have also determined from the low percentage of the total number of lire alarm calls which are received within the same time in erval that it practically unnecessari to provide more than two of such trunks, the desirability of which is at once apparent from the sureness of operation of the pparatus and from the low cost of installation as compared with the expense Speciiication of Letters Patent.

Patented May 15, 1&1?

Serial No. 820,949.

that would be incurred by unduly increasing the number of said trunks, and although my invention is not to be considered as limited in any way to a duplex trunking scheme, it will be understood that I prefer this circuit arrangement for the reasons previously given.

In the illustration I have shown two tele phone subscribers instrument circuits, comprising the line vires LA and B, B pro vided with the usual telephone sets and equipped with alarm signaling mechanisms, such as a call box, indicated generally by revoluble notched wheels A", B which open and close the pairs of contacts a and b in each of said circuits when the box mechanisms are set into operation. The subscribers circuits terminate at the central ofiice or telephone exchange in the usual terminals of the switchboard jacks A B each of which comprises the tip, ring and sleeve contacts a, a and c and 7), b and 6 The tip and ring contacts are connected with the line wires of their respective subscribers stations in the usual manner, as indicated by the wires (i a and 5*, Associated with each of these ircuits are the usual line relays, as indicated by a and b, and cutoff relays a, b which perform their usual functions. The main battery or source of current, indicated by 4:, is connected at its positive pole by the wires a and b wh'ch are connected respectively with the sleeve a, of the jack A and the slec e 72 of the jack B, said sleeves being hereafter referred to as the battery terminals.

The two out-going trunk circuits leading to the fire alarm headquarters comprise the pairs of wires F, F and G, G which lead to the two independent alarm and recording mechanisms F These circuits are each supplied over one limb with current from the negative side of the main battery X, the other limbs being grounded through high resistance relays f, 5 said grounds being indicated by f, 1/. It will be understood that the tive pole, as indicated at w. The trunks are, therefore, constantly supplied with current, but by reason of the high resistances interposed in the circuits the alarm and recording apparatuses being of low resistance are normally restrained from being operated, and, I am, therefore, enabled to combine with these circuits a testing apparatus, which is battery X is grounded at its posi-' to the conductors f f normally inoperative, but which will be set into action to indicate an inoperative condition due to an opening of the trunk. Each of these relays f and g are provided with a normally open pair of contacts which, in respect to relay 7 are indicated by 7, f in a local circuit consisting of the wires f P, which include a buzzer, or other form of indicator G and a battery It will be seen that if the trunk circuit is open the high resistance relay f releases its contacts which close the local circuits and energizes the buzzer f.

In order to guard the trunk circuits against grounding and to give an alarm in the event such a thing occurs, 1 also provide one of the limbs of each trunk with a relay coil 7, g which normally maintain in open condition a pair of contacts i f attached The signals are despatched over the trunk circuits by the opening and closing of a pair of contacts in each indicated by F and G the movement of which is controlled by the repeating relay F G included in the central office apparatus.

The arrangement of the switchboard circuits or central office apparatus, which serves as a means of connection between the subscribers circuits and one or another of tho fire alarm trunks, and performs the switchin operations, is associated with the cord circuits, two of which are arranged at each switchboard operators section, and are gen erally designated as the fire plugs. Two of these are shown in the drawing and indicated by C and D, but there may be any number of them depending upon the size of the switchboard, and which with the associated apparatus acts to perform their functions when a fire alarm signal is despatched over one of the trunks by the insertion of one of the fire plugs in one of the jacks, to automatically switch all of the other plug circuits onto the second trunk. Thus, it will be seen, that should it happen that two fire alarm signals are received by the same, or different, telephone operators it would be impossible to connect the respective subscribers circuits with one and the same trunk.

In further describing the alarm trunk circuits it may be said that each of these include an eleetro-magnet F G which for convenience will be termed the repeater since they repeat the impulses received from the signaling apparatus of the subscribers line and cause corresponding impulses to be transmitted to the signal devices F Both of these magnets are adapted to be energized by current received when one or the other of the plugs C and D are inserted in the line acks, but the switching mechanism controls their circuits in such manner that only one of them can be energized at one time by the act of inserting a single plug. Further, when one magnet is energized and an alarm trunk is seized by the use of one plug the conjoint actionof the switching relays causes the other magnet to be appropriated to and become capable "of operation only by the second plug. Two of the strands of each plug are adapted to complete the subscribers line circuit to one or the other of the repeater magnets F G and by an arrangement of contacts on the switching relays C, D normally closed branch circuits extend from each magnet to each plug and a normally open branch like 'wise extends from one of the magnets to both plugs. When a call is initiated by the insertion of a plug in a jack, the normally closed branch is opened and the seizure of the alarm trunk is caused by closing the open branch circuit. Since both of these open branch circuits control the one magnet (F it therefore becomes the primary alarm trunk and will transmit the signals irrespective of which plug is used providing only one alarm is answered. The other or secondary alarm trunk will receive the second or subsequent call which may come in during the time the primary trunk is occupied and it is also immaterial as to which of the two plugs is used in answering the second call.

To this end there is associated with each cord circuit the switching relays C and D, one terminal of each of said relays being connected by the wires 0 and d to the sleeve or battery contacts 0 and cl. of their respective cord plugs, the other terminals of said relays being tied to the negative side of the battery by the leads 0 d connected with the common battery return wire X. Relay O controls a pair of normally closed contacts 1 and 2, and two pair of normally open contacts 3 and 4:, and 5 and 6, the last mentioned contact spring being adapted when disengaged from spring 5 to engage spring 7 The corresponding contacts on D are indicated by 10, 20, 30, 40, 50, and 7 0.

The tip contact 0 of the plug G is grounded over the wire c" and the ring contact 0 is connected by the wire 0 with a relay contact spring 6 which, when in engagement with spring 7 completes the circuit over the wire 0 to one terminal of the repeating relay F the other terminal of said relay being connected to the battery lead X by the wire 0 Associated with the switching relays C, D are cutoff relays C D the former being provided with contacts 8 and 9, while the latter is provided with similar contacts 80 and 90. The contact 8 is connected with the wire 0 by the tap e and the spring 9 is joined to the spring 2 by the wire 6, likewise the spring 1 is connected with the wire 0 by the lead 6 One terminal of the coil C is grounded by the wire 6 while the other terminal is connected by the wire 0 with the contact spring l, and the mate spring 3 is joined by the wire 6 with the battery lead X. In connection with this group of contacts it only remains to be said that the spring 4 is connected by the wire with the contact spring of the other set. of relay contacts; the contacts 5 and are tied together by the wire and the contacts 7 and are connected by the wires 0 and 77. It will be noticed that one terminal of the coil of the cutoff relay D is grounded over the wire (Z and the other end of the coil is connected to the contact spring l0 by the wire (Z also that the contacts 20 and are connected by the wire 29 and that the contact 80 is joined to the conductor (Z by the wire (Z repeating relay G for the second til ve a: billlll; 11115 10 O; lbb ne-lllllildio Cdililtcufirl to the wi 05 and 56 and its other extremity join d to the coiuluctor (Z the wire 57, and at th rint it will be noted that the wire connected with the l atteiy lead X. ()5 the pairs oi contacts G of the second trunk one connected to the ground g which is also the terminal f 01- end of the coil g a d the other contact is connected to the coil tid t the wire 6* p a ratus coin prisin described, 1 ay al the opposite car alarm t1 1,

the two pairs of nori'nally open or ntacts g on the rel g, and 9' 5 on the rela it 0 MG r. and connectin .l oy the w e g and g with the onduc ors of the circuit of the buzzer or indicator f Describing the operation of the apparatus scriczz'm it will be assumed first, to facilitate a clear und rstanding the oporation or". the rarious relays and sets of contacts, that alarm signals are turned in or despatched from only one of the sul scribers stations omitting the complications which ensue wien two-fire alarm calls are received simultaneously. When a subscrihers alarm nrechanism is operated the central othce operator ugon answ 1; the call in the usual manner with the plug in an answering d circuit she receives a distinctive signal whi h informs her that the alarm mechanism is in opev.tion and that the impulses o'l' cu ent despatc led to the central oilice 2'@ not to line disturb one this distinctive es The n i by whicn is t or e such as that 1 inc; th suhiec l) nt hlo ,0-OS.3l3. granted November 14, lf ll to ll illiam llfllenio or shown in my pending application. Serial No, 711 4? for patent for fire ale-*1 apparatus, filed July 25, 1912. As abor stated, the central ofiice operator upon patch of a fire alarm signal 0 de ices F G Use-n the insertion the plug into the jack]? the follcu in conditions are established Grouno is applied to side of the subsc 'ibers circuit; the swit hing relay C is connected to the po itive side of the battery and becoming energized shifts its contacts, and the repeating relay F is con nected to the subscribei"s circuit. the contacts 6 and 7 being closed. The flow of current through the switching relay C may be traced Yer the following ci cuit: battery X, wire a cutoff relay a sl contacts a. 0 wire 0, coil C wire 0 resis ance J. wire X to battery. Similarly the circuit oi the repeating relay F may be tracel as follows: battery X wires X, a coil l wire 0 contacts 7 (3, wire 0", spring contacts 0, (4 i use of springs a, wires A, a spring 0'. tip wire 0* through ground to battery. The opening and closing of the contacts at the subscribers station produce a corresponding movement of the normally open contacts i of the first fire alarm trunk, which latter may be traced as follows: battery X, wire K, coil 7, conductor F to the bell and recorder F thence the wire F to the pair of contacts F to ground f, thence to the battery. Qontact 3 is tied to side of the battery that when it is c o ed into engagement with the spring l the circuit is completed from battery wires X", 0", contacts 3 and 's, vire e coil C wire 6* to ground and the energizing of the last mentioned coil closes the normally open contacts 8 and 9, the eft'ect of which is counteracted by the opening of the corresponding normally closed contacts 1 and These conditions just described with respect to the switching relay C and cutolli relay will be produced by the insertion of the plug C in any subscribers line jack. Upon the inso on of the plug D in any of the acks its COIJlfQSlM'HlCll 9' switching relav and cute r la 4 2 l be ner I r e i i and the alarm signal impulses rope the fir st trunk F. upon the op v t closin or the contacts on the rene relay providing. of l is idle.

The switching of the fire plug cord circuits is such that in the c ent any one or" a cults, that is the remaining nine, are left on the r ..:r fire alarm trunk circuit, and it is, theieiore, impossible to confound theopeiation of the signaling and indicating mechanism at fire department he dqumters, as would otherwise result should it happen that two different switchboard operators both selected one fire alarm trunk at the same time. When the switchin relay C is energized in answer to the first incoming fire alarm call, the cutoff relay D is also energized by current flowing over the following circuit: battery X, wires X, a spring contacts 3 and i, wires 44:, (Z coil D wire (Z to ground nd thence to battery. The closing of the contacts 80 and 90 completes a shunt circuit around the coil. of the switching relay D which condition exists as long as the relay C is energized, with the consequent result that, if. during this time, the plug 1) is inserted in the jack D it can only effect the operation of the repeater G and despatch signals over the second. fire alarm trunk G, G as follows: The second fire alarm signal being received while the first signal is being transmitted, as previously described, and the plug D inserted in the jack D the battery circuit which is completed through the sleeve contacts 79 and d leads around the coil D over the wire (3 contacts 10 and 20, wire 29, contacts 90 and 80 and wire The contacts 50 and 60 thereupon remain in their normal condition and the complete circuit of the repeating relay may be described as follows: battery X, wires X, 57, coil G wires 56, 55, contacts 50 and 60, wire (Z rings (Z 6 wires 7) and B, signaling contacts 7), wires B, 72 tip spring 7) and contact cZ ,wire (Z to ground and battery.

Reference heretofore to the first and second fire alarm trunk circuits necessarily pre sages the particular order of operation in respect to the two trunks F, F and G, G, although either may be arranged to be the first to receive an incoming call, but in the arrangement shown if the plug D is inserted in the pick B while the plug C remains idle, the repeating relay F is seized and the following conditions established: The switching relay 1) is energized by current flowing over the following circuit: hatter X. wire 6 coil 7W, sleeves 79 (1, wire (Z coil D, wire (Z resistance J, wire X to battery, As a result of this contacts 10 and are open. while the springs and are closed and and are brought together l i hen contact 30 engages spring 40 the former, which is connected to the wire X by the lead. 30*, connects battery to coil C the complete circuit being traceable as fol lows: battery X, wires X, 30*, springs 30; and 40. wires 44-, e 0011 C wire 6 to ground" and battery. The coil C now closes its con tacts 8 and 9 which completes the shunt c1r cuit for the relay C, which circuit is lndi cated by a wire 6 contacts 1 and 2, wire 0, contacts 8 and 9 and wire 0, which latter is connected to the conductor 0 The closing of the contacts 60 and 70 effects the selection of the first fire alarm trunk by the energizing of the repeater F the circuit of which will seen to extend as follows: battery 1, wires X, 0 coil F wire 77, contacts 7 O, 60, wire a, ring contacts (Z and 6 wires 7), B, contacts 6, wires B, 5 tip spring 7), contact 6Z3, wire d to ground and battery.

It will now be seen that when the second incoming fire alarm call is received over the cord circuit C, the contacts of the switching relay C remaining in their normal position,

said call will traverse the following circuitz battery X, wires X, (P, 57, coil G wires 56, 55, contacts 5 and 6, wire 0 ring contact 0, a wires a, A, contact 64, wires A, c tip spring a and contact 0 wire 0 to ground and battery. Coil G, therefore, causes the contacts G to be closed and opened and the alarm impulses reproduced in the signal devices G I claim as my invention:

1. The combination with a plurality of telephone lines each provided with impulse despatching mechanism and terminating in line jacks at the central office, of a plurality of plugs each comprising. a repeater trunk adapted to be connected with the telephone lines and having normally open contacts, relays for closing the latter adapted to be energized when the plugs are inserted in the jacks, of means for short circuiting the relay of one trunk when the other relay is operated.

52. In a telephone fire alarm trunk switching mechanism, the combination with two separate sets of signal apparatus, and a plu rality of subscribers telephone lines including telephone sets each line provided with means independent of said telephone sets for despatching impulses of current thereover, of central oliice switchboard mechanism for connecting the subscribers lines with the signal apparatus comprising means cooperating with both sets of signal apparatus and serving to seize one set for the first incoming call and switch subsequent incoming calls onto the other set of signal apparatus.

3. In an alarm trunk signal switching mechanism for telephone fire alarm systems, the combination with a plurality of sub scribers lines, of separate sets of alarm mechanisms, an alarm signal despatching mechanism on each subscribers line and operable independent of the normal functions of said line, a plurality of means for con- ;necting the different lines and one or another of the alarm mechanisms upon the 0p- 'eration of a despatching mechanism, and apparatus associated with said connecting means for automatically appropriating one arm mechanisms to one of the sub- Lines and rendering the other alari ism capable only of being connected .ilier subscribers line.

l. in an alarm trunk signal switching mechanism, the combination with a telephone exchange system comprising a plurality of subscribers lines and a plurality of alarm trunks, of switch board plug circuits for connecting the subscribers lines to the alarm trunks, and apparatus for connecting the plug circuits with one or anoth r of the alarm trunks and serving when one trunk is connected to a line to connect the other plugs to the idle alarm trunk.

5. In a fire alarm telephone system, the mmbination with a plurality of subscribers lines, a central exchange, a plurality of alarm trunks and a plurality of p ug circuits for connecting said lines and trunks, of an automatically operated switching apparatus, controlling the connections between the plug circuits and trunks and acting to seize one trunk upon the connection of a plug to a line and to connect the remaining plu s to the other trunk.

6. The combination with a plurality of telephone sub cribers lines and a central exchange switch board having a plurality of operators stations and a fire alarm plug circuit for each station connected in multiple and two impulse repeaters arranger. to be controlled by the plug circuits, of separate alarm trunks governed by said repeaters, and switching devices controlling the seizure of one or" the repeaters when a plug is connected to line and. also controlling the connection of the remaining plugs to the other repeater.

7. The combination with a plurality of telephone subscribers lines and a central xchange switch board having a plurality of operators stations and a fire alarm plug circuit for each station, two sets of alarm apparatus arranged to be operated by current impulses over one or another of the plug circuits, of switching devices controlling said plug circuits and acting when one of the latter is connected to a line to appropriate thereto one of the alarm apparatuses and to connect the other plug circuit to the second alarm apparatus.

8. In a te ephone system, the combination with a switch board having line jacks, subscribers lines terminating therein, said jacks having a third contact supplied with current, a plurality of alarm apparatus circuits having contacts and comprising alarm switch board plugs adapted to connect the alarm circuits to the subscribers lines, a third contact on each plug adapted to co operate with the third contact of the jacks, a relay controlling each alarm apparatus circuit and having circuits including the third contact of their respective plugs which are energized when said plugs are inserted in jacks and. means capable oi operation by each relay for rendering all of the other relays inoperative.

9. In a alarm telephone system, the combination with a plurality of subscribers circuits and two alarm apparatuses each comprising an electromagnet, of two alarm trunks each comprisin two divisions one being a normally closed circuit connected to one magnet and the other a normally open circuit connected to the other magnet, a re lay associated with each trunk and adapted to be energized when a trunk is connected to a line-and acting to reverse the condition m the trunk contacts, means also controlled by each relay when energized for rendering the other relay inoperative.

10. In a trunk switching mechanism, the combination with an apparatus embodying two magnets, two trunks each having two branches including each of said magnets, one of said branches of each trunk being normally closed and the other being normally open, of a relay associated with each trunk and adapted when energized to reverse the condition oi the branches of its respective trunk and means controlled by each relay when it is energized for rendering the other relay inoperative.

11. The combination with a telephone system comprising subscribers circuits terminating in line jacks at central oilice, said jacks also having a third contact supplied with battery, of an alarn apparatus comprising two magnets, trunks having plugs adapted to cooperate with the jacks and to connect them to the subscribers circuits, each of said plugs also having a third terminal cooperating with the battery contacts of the jacks, two branch circuits for each trunl: connected o the magnets and contacts controlling the connections of the trunks with their respective branches, relays for operating the latter, each having a circuit connected to the third contact or" a plug and adapted to be energized when the latter is inserted in a jack and other circuits also controlled by each relay when operated for rendering the other relay inoperative.

12. The combination with a plurality of subscribers telephone lines terminating in line jacks at central oiiice, said jacks being also provided with a battery terminal, a plurality of plugs adapted to cooperate with said jacks each having two strands forming an alarm trunk adapted to be united with the subscribers lines and a third conductor adapted to be joined to the battery terminal of a jack, of relays located in each of the third conductors and each adapted to be energized when its respective plug is inserted in a jack, alarm mechanisms comprising a plurality of electromagnets each having two circuits, one closed with and the lee other adapted to be closed with the strands oi one of the plugs and arranged to have their connections reversed by the energizing of their respective relays and means also controlled by the latter so that upon the energizing of one relay the other relays will be rendered inoperative.

13. In a telephone system, the combination with a plurality of subscribers circuits, a central oifice switch board apparatus comprising subscribers line jacks and two alarm trunk cord circuit plugs and primary and secoiulary alarm mechanisms each comprising an elcctro-magnet, or a switching relay for each. cord circuit arranged to be energized when its respective plug is inserted in a jack, strands in the plugs adapted to form continuations of the subscribers circuits, two normally open branch circuits leading from the magnet of the primary alarm mechanism adapted to be connected to subscribefis circuit by the action of either of the switching relays, other circuits leadfrom each of said magnets and normally connected in circuit with the plug strands, and means for rendering either of said switching relays inoperatiye when the other has been energizec.

li e. The combination with a plurality of primary circuits, of a plurality of secondary circuits, relays for establishing communication between any two of said circuits and i 1 .t'or making the remainder of said relays inoperative, to establish communication between two other of said circuits.

The combination with a plurality of primary circuits, of a secondary circuit, relays for establishing communication between any one of said primary circuits with said secondary circuit, and means for making the remainder of said relays inoperative during such communication.

16. T he combination with a plurality of primary circuits, of a secondary circuit, relays for establishing communication between any one of said primary circuits with said secondary circuit, associated relays adapted to he energized upon such communication being established, and means for making an idle one or said first relays simultaneous y inoperative.

17. in a telephone fire alarm trunk switching mechanism, the combination with two of signal apparatus, and a plurality of subscribers telephone lines, each including a telephone set and an independent mechanism for despatching current impulses over said line, oi central o'llice switchboard. mechanism for connecting the subscribers lll as with the signal apparatus, comprising means cooperating with both sets of signal appa and serving to seize one set for the first incoming call despatched by an impulse mechanism aforesaid and switch subsequent incoming calls on to the other set of signal apparatus.

1.". in telephone fire alarm trunk switching mechanism, the combination with a switchboard, of subscribers lines extending therefrom, and a plurality oi trunks leading to said switchboard, of a signal apparatus connected to each trunk, a signal despatching mechanism on each subscribers line independent of the subscribers telephone set, and means at the switchboard cooperating with all of said trunks and serving to seize one trunk for the first incoming call from a signal despatehing mechanism aforesaid and switch subsequent incoming calls on to the other trunks.

DAVID G. DEE. Witnesses HYMAN L. WEIss, B. B. CLARK.

Copies of this patent may be obtained for: five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

